Synergistic microbicidal combinations containing 2-n-octyl-3-isothiazolone and certain commercial biocides

ABSTRACT

Synergistic antimicrobial and biocidal compositions comprising 2-n-octyl-4-isothiazolin-3-one and one or more known biocides for more effective, and broader control of microorganisms in various industrial systems are disclosed.

This is a divisional application Ser. No. 539,254, filed Jun. 18,1990,now U.S. Pat. No. 5,041,457, which is a divisional of Ser. No. 322,455,filed Mar. 10, 1989, now U.S. Pat. No. 4,964,892, which is acontinuation-in-part of Ser. No. 288,529, filed Dec. 22, 1988, nowabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to synergistic antimicrobial or biocidalcompositions including an isothiazolone and one or more of knownbiocides for more effective and broader control of micro-organisms invarious industrial systems and for household products, agriculturalproducts, and biomedical products, etc. In particular, the presentinvention relate to the use of a composition of2-n-octyl-4-isothiazolin-3-one (also known as 22-n-octyl-3-isothiazolone or 2-n-octylisothiazolone) with one or more ofthe following 21 compounds: 2-(hydroxymethyl)amino-2-methylpropanol;2-(hydroxymethyl)aminoethanol; 5-bromo-5-nitro-1,3-dioxane;hexahydro-1,3,5-triethyl-s-triazine; α-benzoyl-α-chloroformaldoxime;benzylbromoacetate; p-chloro-m-xylenol;bis-(2-hydroxy-5-chlorophenyl)sulfide; p-tolyldiiodomethylsulfone;3-iodo-2-propynylbutylcarbamate;5-hydroxypoly(methyleneoxy)-methyl-1-aza-3,7-dioxabicyclo(3,3,0)octane;dipropylamine ether; dodecylamine;N-(hydroxymethyl)-N-(1,3-di(hydroxymethyl)-2,5-dioxo-4-imidazolidinyl-N'-(hydroxymethyl)urea;1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride;1,2-dibromo-2,4-dicyanobutane;N,N-dimethyl-N'-phenyl-N'-(fluorodichloromethylthio)sulfamide;N,N'-di(hydroxymethyl)-5,5'-dimethylhydantoin;2-bromo-2-nitropropanediol; methylene-bis-thiocyanate; and2,4-dichlorobenzyl alcohol.

2. Prior Art

The isothiazolones are described in U.S. Pat. Nos. 3,761,488; 4,105,431;4,242,694; 4,265,899 and 4,279,762, and elsewhere. The2-n-octyl-4-isothiazolin-3-one (octhilinone) is a superior fungicidewith relatively lower activity against Gram-negative bacteria. The lowactivity against Gram negative bacteria has limited its uses inindustrial systems where both bacteria and fungi are fouling thesystems. To control these situations requires a higher concentration ofocthilinone, which increases the cost of the treatment. Therefore, it isuseful to find compositions which are more effective and exert broadercontrol.

It has been discovered that compositions formed from2-n-octyl-4-isothiazolin-3-one and one or more of the 21 specifiedcompounds (supra) within specified range of ratios unexpectedly affordedsynergistic antimicrobial activity against a wide range ofmicroorganisms. The synergy in which the disruptive action on theorganisms by the two compounds together is greater than the sum of bothcompounds taken alone does not arise from the expected activity of thecomponents or from the expected improvement in activity. As a result ofthe synergy, the effective dose which can be lowered is not only moreeconomical but also increases safety margin. The synergisticcompositions provide more effective and broader control ofmicroorganisms in a number of industrial systems.

It is the principal object of this invention to provide the use ofsynergistic compositions which overcome the disadvantages of the knownbiocidal compositions.

Important applications of the synergistic antimicrobial compositions ofthe present invention include but are not limited to: inhibiting thegrowth of bacteria and fungi in aqueous paints and coatings, adhesives,sealants, latex emulsions, and joint cements; preserving wood;preserving cutting fluids, controlling slime-producing bacteria andfungi in pulp and papermills and cooling towers; as a spray or diptreatment for textiles and leather to prevent mold growth; protectingpaint films, especially exterior paints, from attack by fungi whichoccurs during weathering of the paint film; protecting processingequipment from slime deposits during manufacture of cane and beet sugar;preventing microorganism buildup and deposits in air washer or scrubbersystems and in industrial fresh water supply systems; preserving fuel;controlling microorganisms contamination and deposits in oil fielddrilling fluids and muds, and in secondary petroleum recovery processes;preventing bacterial and fungal growth in paper coatings and coatingprocesses; controlling bacterial and fungal growth and deposits duringthe manufacture of various specialty boards, e.g., cardboard andparticle board; preventing sap stain discoloration on freshly cut woodof various kinds; controlling bacterial and fungal growth in clay andpigment slurries of various types; as a hard surface disinfectant toprevent growth of bacterial and fungi on walls, floors, etc.; as apreservative for cosmetic and toiletry raw materials, floor polishes,fabric softeners, household and industrial cleaners; in swimming poolsto prevent algae growth; inhibiting the growth of harmful bacterial,yeasts, fungi on plants, trees, fruits, seeds, or soil; preservingagricultural formulations, electrodeposition systems, diagnostic andreagent products, medical devices; protecting animal dip compositionsagainst the buildup of microorganisms, and in photoprocessing to preventbuildup of microorganisms, and the like.

The synergistic compositions of the invention may be added separately toan industrial system or may be formulated as a simple mixture comprisingits essential ingredients, and if desired a suitable carrier or solvent,or as an aqueous emulsion or dispersion.

SUMMARY OF THE INVENTION

Compositions of octhilinone and one or more of the following compoundswhen employed at specified range of ratios exhibit synergistic biocidaland anti-microbial activity against a wide range of microorganisms:2-(hydroxymethyl)amino-2-methylpropanol; 2-(hydroxymethyl) aminoethanol;5-bromo-5-nitro-1,3-dioxane; hexahydro-1,3,5-triethyl-s-triazine;α-benzoyl-α-chloroformaldoxime; benzylbromoacetate; p-chloro-m-xylenol;bis-(2-hydroxy-5-chlorophenyl)sulfide; p-tolyldiiodomethylsulfone;3-iodo-2-propynylbutylcarbamate;5-hydroxypoly(methyleneoxy)-methyl-1-aza-3,7-dioxabicyclo(3,3,0)octane;dipropylamine ether; dodecylamine;N-(hydroxymetyl)-N-(1,3-di(hydroxymethyl)-2,5-dioxox-4-imidazolidinyl-N'-(hydroxymethylurea;1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride;1,2-dibromo-2,4-dicyanobutane;N,N-dimethyl-N'-phenyl-N'(fluorodichloromethylthio)sulfamide;N,N'-di(hydroxymethyl)-5,5'-dimethylhydantoin;2-bromo-2-nitropropanediol; methylene-bis-thiocyanate; and2,4-dichlorobenzyl alcohol.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention also relates to a method of inhibiting the growth ofbacteria, fungi or algae in a locus subject to contamination bybacteria, fungi or algae, which comprises incorporating into or onto thelocus in an amount which is effective to adversely affect the growth ofbacteria, fungi or algae one or more of the synergistic combinationsdescribed above.

The composition of the invention can be formulated as a solution inwater. While the amount of the instant composition in the formulatedsolution can vary over a wide range, the solutions can conveniently beformulated to contain from about 20 to about 400 ppm of the compositionin solution, with the preferred range being from about 25 to 200 ppm ofthe composition. In formulating the solutions, other solvents which arewater-miscible, such as ethyl alcohol, propyl alcohol, isopropylalcohol, diethylene glycol, dipropylene glycol, polyethylene glycol,diethylene glycol, ethyl ether, and the like, may be employed in orderto aid in solubilizing the active components. Furthermore, various otherconventional additives may be employed, such as surfactants, dispersingagents, corrosion inhibitors, and the like.

In general, the ratio of the first component to second component is therange of from about 150:1 to about 1:400. The other specific andpreferred ratios are given in the examples.

The synergism of these two-components compositions is demonstrated bytesting a wide range of concentrations and ratios of compounds,generated by two-fold serial dilutions in a liquid growth medium of abiocide in one dimension and another biocide in the second dimension,against a bacterium Escherichia coli (ATCC 11229) or a fungus Candidaalbicans (ATCC 11651), or a mixed culture of bacterial and fungi whichare natural contaminants of a metalworking fluid. Each test tube wasinoculated to about 2×10⁷ bacteria per ml or 2×10⁶ fungi per ml. Thelowest concentrations of each compound or mixtures to inhibit visiblegrowth (turbidity) at 37° for E. coli and at 30° C. for C. albicans, orthe mixed culture for over 2 days is the minimum inhibitoryconcentration (MIC). The lowest concentration of each compound or themixtures to kill 99.99% of fungi or 99.999% of bacteria after certainperiod of exposure from 1 day to 7 days is taken as minimum biocidalconcentration (MBC). Both MIC and MBC are taken as end points ofactivity. End points for the mixtures of compound A and compound B werethen compared with the end points for compound A alone and compound Balone. Synergism was determined by a commonly used and accepted methoddescribed by Kull, F. C.; Eisman, P. C.; Sylwestrowicz, H. D. and Mayer,R. L., in applied Microbiology 9:538-541 (1961) using the ratiodetermined by

    Qa/QA+Qb/QB=Synergy Index (SI)

wherein

QA=concentration of compound A in parts per million (ppm), acting alone,which produced an end point.

Qa=concentration of compound A in ppm, in the mixture, which produced anend point.

QB=concentration of compound B in ppm, acting alone, which produced anend point.

Qb=concentration of compound B in ppm, in the mixture, which produced anend point

when the sum of Qa/QA and Qb/QB is greater than one, antagonism isindicated. When the sum is equal to one additivity is indicated, andwhen less than one synergism is demonstrated.

The test results for demonstration of synergism of biocide combinationsare shown in Table 1 through Table 21. Each table is organized to show:

1. the specific combination of compound A and compound B;

2. test against E. coli or C. albicans, or a mixed culture of bacteriaand fungi;

3. test medium by either trypticase soy broth (TSB) or a minimal saltmedium+0.2% glucose (M9G);

4. the method of evaluation by either MIC or MBC. The MBCld means MBCdetermined after 1-day exposure to biocides. MBC2d means MBC determinedafter 2-days exposure to biocides, etc.;

5. the end-point activity in ppm measured by MIC or MBC for compound Aalone (QA), for compound B alone (QB), for compound A in the mixture(Qa), or for compound B in the mixture (Qb);

6. the calculation for synergy index (SI) based on the formulaSI=Qa/QA+Qb/QB, and for the ratio of compound A to compound B in thesynergistic combinations (Qa:Qb);

7. the range of ratios for synergism and the preferred ratios.

                  TABLE 1                                                         ______________________________________                                        Combination of Octhilinone and 2-(Hydroxymethyl)amino-2-                      methylpropanol                                                                Compound A = Octhilinone                                                      Compound B = 2-(Hydroxymethyl)amino-2-methylpropanol                          Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against C. albicans in TSB medium                                        MIC     2.5   1000.0   1.3 500.0                                                                              0.50 0.50 1.00  1:400                         test against E. coli in M9G medium                                            MIC    125.0   62.0    2.0  31.0                                                                              0.02 0.50 0.52  1:16                                 125.0   62.0    8.0  16.0                                                                              0.06 0.26 0.32 1:2                                   125.0   62.0   62.0  8.0 0.50 0.13 0.63 8:1                            MBC1d  250.0   250.0  16.0  31.0                                                                              0.06 0.12 0.19 1:2                                   250.0   250.0  31.0  16.0                                                                              0.12 0.06 0.19 2:1                                   250.0   250.0  62.0  8.0 0.25 0.03 0.28 8:1                            MBC4d  125.0   62.0    2.0  31.0                                                                              0.02 0.50 0.52  1:16                                 125.0   62.0     8.0                                                                               16.0                                                                              0.06 0.26 0.32 1:2                                   125.0   62.0   62.0  8.0 0.50 0.13 0.63 8:1                            MBC7d  125.0   62.0    2.0  31.0                                                                              0.02 0.50 0.52  1:16                                 125.0   62.0    8.0  16.0                                                                              0.06 0.26 0.32 1:2                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 8:1 to 1:16.       The preferred ratios are 1:2 to 1:16.                                    

                  TABLE 2                                                         ______________________________________                                         Combination of Octhilinone and 2-(Hydroxymethyl)aminoethanol                 Compound A = Octhilinone                                                      Compound B = 2-(Hydroxymethyl)aminoethanol                                    Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0   62.0    4.0  31.0                                                                              0.03 0.50 0.53 1:8                                   125.0   62.0   62.0  8.0 0.50 0.13 0.63 8:1                            MBC1d  250.0   500.0  62.0  16.0                                                                              0.25 0.03 0.28 4:1                            MBC4d  125.0   62.0    4.0  31.0                                                                              0.03 0.50 0.53 1:8                                   125.0   62.0   62.0  8.0 0.50 0.13 0.63 8:1                            MBC7d  125.0   62.0    4.0  31.0                                                                              0.03 0.50 0.53 1:8                                   125.0   62.0   62.0  8.0 0.50 0.13 0.63 8:1                            test against C. albicans in TSB medium                                        MIC     1.3   1000.0   0.6  31.0                                                                              0.50 0.03 0.53  1:50                          MBC1d   1.3   1000.0   0.6 125.0                                                                              0.50 0.13 0.63  1:200                         MBC4d   1.3   1000.0   0.6 125.0                                                                              0.50 0.13 0.63  1:200                         ______________________________________                                         The synergistic ratios of compound A:compound B range from 8:1 to 1:200.      The preferred ratios are 1:8 to 8:1                                      

                  TABLE 3                                                         ______________________________________                                         Combination of Octhilinone and 5-Bromo-5-nitro-1,3-dioxane                   Compound A = Octhilinone                                                      B = 5-Bromo-5-nitro-1,3-dioxane                                               Method             calculations                                               of eval-                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                             uation QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                           ______________________________________                                        test against E. coli in TSB medium                                            MBC    125.0  50.0   16.0 25.0 0.13 0.50 0.63   1:1.6                         MBC    125.0  50.0    2.0 25.0 0.02 0.50 0.52   1:1.25                        test against C. albicans in TSB medium                                        MIC     2.0   25.0    0.5 3.1  0.25 0.12 0.37   1:6.2                                 2.0   25.0    1.0 0.1  0.50 0.00 0.50   10:1                          MBC2d   2.0   25.0    1.0 0.4  0.50 0.02 0.52  2.5:1                          MBC6d   2.0   25.0    1.0 0.8  0.50 0.03 0.53  1.2:1                          test against E. coli in M9G medium                                            MIC    125.0  10.0   62.0 0.6  0.50 0.06 0.56  100:1                                 125.0  10.0   16.0 2.5  0.13 0.25 0.38  6.4:1                                 125.0  10.0    2.0 5.0  0.02 0.50 0.52   1:2.5                         MBC1d  125.0  20.0   62.0 0.6  0.50 0.03 0.53  100:1                                 125.0  20.0   31.0 2.5  0.25 0.13 0.37 12.5:1                                 125.0  20.0    8.0 5.0  0.06 0.25 0.31  1.5:1                          test against a mixed culture in TSB medium                                    MIC    250.0  12.5    8.0 5.0  0.03 0.40 0.43  1.5:1                          MBC1d  250.0  50.0   31.0 20.0 0.12 0.40 0.52  1.5:1                          MBC2d  250.0  50.0   31.0 20.0 0.12 0.40 0.52  1.5:1                          MBC6d  250.0  12.5    8.0 5.0  0.03 0.40 0.43  1.5:1                          ______________________________________                                         The synergistic ratios of compound A:compound B range from 100:1 to           1:12.5. The preferred ratios are 1.5:1 to 1:12.5.                        

                  TABLE 4                                                         ______________________________________                                         Combination of Octhilinone and Hexahydro-1,3,5-triethyl-s-triazine           Compound A = Octhilinone                                                      Compound B = Hexahydro-1,3,5-triethyl-s-triazine                                                calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evaluation                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G                                                   MIC     125.0   16.0  62.0 4.0  0.50 0.25 0.75 16:1                           MBC1d   250.0  125.0  62.0 16.0 0.25 0.13 0.38  4:1                           MBC4d   125.0   16.0  62.0 4.0  0.50 0.25 0.75 16:1                           MBC7d   125.0   16.0  62.0 4.0  0.50 0.25 0.75 16:1                           ______________________________________                                         The synergistic ratios of compound A:compound B range from 4:1 to 16:1.       The preferred ratios are 4:1 to 16:1.                                    

                  TABLE 5                                                         ______________________________________                                         Combination of Octhilinone and α-Benzoyl-α-chloroformaldoxime    Compound A = Octhilinone                                                      Benzoyl-α-chloroformaldoxime                                            Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0   500.0   8.0 125.0                                                                              0.06 0.25 0.31  1:15                                 125.0   500.0   31.0                                                                               62.0                                                                              0.25 0.12 0.37 1:2                                   125.0   500.0   62.0                                                                               31.0                                                                              0.50 0.06 0.56 2:1                            MBC1d  250.0   500.0   4.0 250.0                                                                              0.02 0.50 0.52  1:62                                 250.0   500.0   62.0                                                                               62.0                                                                              0.25 0.12 0.37 1:1                                   250.0   500.0  125.0                                                                               2.0 0.50 0.00 0.50 62:1                           MBC4d  125.0   500.0   8.0 125.0                                                                              0.06 0.25 0.31  1:15                                 125.0   500.0   31.0                                                                               62.0                                                                              0.25 0.12 0.37 1:2                                   125.0   500.0   62.0                                                                               31.0                                                                              0.50 0.06 0.56 2:1                            MBC7d  125.0   500.0   8.0 125.0                                                                              0.06 0.25 0.31  1:15                                 125.0   500.0   31.0                                                                               62.0                                                                              0.25 0.12 0.37 1:2                                   125.0   500.0   62.0                                                                               31.0                                                                              0.50 0.06 0.56 2:1                            test against C. albicans in TSB medium                                        MIC     1.0   2000.0   0.3  31.0                                                                              0.25 0.02 0.27  1:100                         MBC2d   2.0   2000.0   0.3  31.0                                                                              0.13 0.02 0.15  1:100                         MBC6d   1.0   2000.0   0.3  31.0                                                                              0.25 0.02 0.27  1:100                         test against E. coli in TSB medium                                            MIC    250.0  2000.0  125.0                                                                               62.0                                                                              0.50 0.03 0.53 2:1                            MBC2d  250.0  2000.0  125.0                                                                               62.0                                                                              0.50 0.03 0.53 2:1                            MBC6d  250.0  2000.0  125.0                                                                               62.0                                                                              0.50 0.03 0.53 2:1                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 62:1 to 1:100.     The preferred ratios are 2:1 to 1:2.                                     

                  TABLE 6                                                         ______________________________________                                         Combination of Octhilinone and Benzylbromoacetate                            Compound A = Octhilinone                                                      Compound B = Benzylbromoacetate                                               Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against C. albicans in TSB medium                                        MIC     2.5   12.5     0.1 3.1  0.03 0.25 0.28   1:40                                 2.5   12.5     0.3 1.6  0.12 0.13 0.25   1:5                          test against a mixed culture in TSB medium                                    MIC    250.0  100.0   62.0 50.0 0.25 0.50 0.75 1.2:1                          MBC2d  250.0  200.0   62.0 50.0 0.25 0.25 0.50 1.2:1                          MBC6d  250.0  200.0   62.0 50.0 0.25 0.25 0.50 1.2:1                          test against E. coli in M9G medium                                            MIC    125.0  12.5    31.0 1.6  0.25 0.13 0.38  20:1                                 125.0  12.5    16.0 3.1  0.13 0.25 0.38   5:1                          MBC1d  125.0  25.0    62.0 1.6  0.50 0.06 0.56  40:1                                 125.0  25.0    31.0 3.1  0.25 0.12 0.37  10:1                                 125.0  25.0    16.0 12.5 0.13 0.50 0.63 1.2:1                          ______________________________________                                         The synergistic ratios of compound A:compound B range from 40:1 to 1:40.      The preferred ratios are 10:1 to 1:5.                                    

                  TABLE 7                                                         ______________________________________                                         Combination of Octhilinone and  -p-Chloro- .sub.-- m-xylenol                 Compound A = Octhilinone                                                      Compound B =  -p-Chloro- .sub.-- m-xylenol                                                      calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evaluation                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC     125.0  250.0   8.0 125.0                                                                              0.06 0.50 0.56  1:15                                  125.0  250.0  62.0  62.0                                                                              0.50 0.25 0.75 1:1                            MBC1d   250.0  250.0   8.0 125.0                                                                              0.03 0.50 0.53  1:15                                  250.0  250.0  62.0  62.0                                                                              0.25 0.25 0.50 1:1                            MBC4d   125.0  250.0   8.0 125.0                                                                              0.06 0.50 0.56  1:15                                  125.0  250.0  62.0  62.0                                                                              0.50 0.25 0.75 1:1                            MBC7d   125.0  250.0   8.0 125.0                                                                              0.06 0.50 0.56  1:15                                  125.0  250.0  62.0  62.0                                                                              0.50 0.25 0.75 1:1                            test against C. albicans in TSB medium                                        MIC      2.5     62.0  1.3  8.0 0.50 0.13 0.63   1:6.2                        test against E. coli in TSB medium                                            MIC     125.0  125.0  62.0  31.0                                                                              0.50 0.25 0.75 2:1                            MBC1d   125.0  125.0  62.0  31.0                                                                              0.50 0.25 0.75 2:1                            MBC2d   125.0  125.0  62.0  31.0                                                                              0.50 0.25 0.75 2:1                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 2:1 to 1:15.       The preferred ratios are 2:1 to 1:15.                                    

                  TABLE 8                                                         ______________________________________                                        Combination of Octhilinone and                                                Bis-(2-hydroxy-5-chlorophenyl)sulfide                                         Compound A = Octhilinone                                                      Compounds B = Bis-(2-hydroxy-5-chlorophenyl)sulfide                                             calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evaluation                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC     125.0  125.0  62.0 31.0 0.50 0.25 0.75 2:1                            MBC4d   125.0  125.0  62.0 62.0 0.50 0.50 1.00 1:1                            MBC7d   125.0  125.0  62.0 62.0 0.50 0.50 1.00 1:1                            test against C. albicans in TSB medium                                        MIC      0.3    31.0  0.1  8.0  0.25 0.26 0.52 1:100                                   0.3    31.0  0.2  2.0  0.52 0.06 0.58 1:10                           MBC1d    0.6    31.0  0.1  8.0  0.13 0.26 0.39 1:100                                   0.6    31.0  0.2  2.0  0.26 0.06 0.32 1:10                           MBC4d    0.6    31.0  0.1  8.0  0.13 0.26 0.39 1:100                                   0.6    31.0  0.2  2.0  0.26 0.06 0.32 1:10                           ______________________________________                                         The synergistic ratios of compound A:compound B range from 2:1 to 1:100.      The preferred ratios are 2:1 to 1:10.                                    

                  TABLE 9                                                         ______________________________________                                        Combination of Octhilinone and  -p-Tolyldiiodomethylsulfone                   Compound A = Octhilinone                                                      Compound B =  -p-Tolyldiiodomethylsulfone                                                       calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evaluation                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in TSB medium                                            MIC     250.0  100.0   2.0 50.0 0.01 0.50 0.51  1:25                                  250.0  100.0  125.0                                                                              0.8  0.50 0.01 0.51 150:1                          MBC2d   250.0  100.0   2.0 50.0 0.01 0.50 0.51  1:25                                  250.0  100.0  125.0                                                                              0.8  0.50 0.01 0.51 150:1                          MBC6d   250.0  100.0   2.0 50.0 0.01 0.05 0.51  1:25                                  250.0  100.0  125.0                                                                              0.8  0.50 0.01 0.51 150:1                          test against C. albicans in TSB medium                                        MIC      4.0    6.2    0.3 0.8  0.06 0.13 0.19   1:3.2                                 4.0    6.2    0.5 0.4  0.13 0.06 0.19 1.2:1                                   4.0    6.2    1.0 0.2  0.25 0.03 0.28 5:1                            MBC2d    4.0    6.2    0.3 0.8  0.06 0.13 0.19   1:3.2                                 4.0    6.2    0.5 0.4  0.13 0.06 0.19 1.2:1                                   4.0    6.2    2.0 0.2  0.50 0.03 0.53 10:1                           MBC6d    4.0    6.2    0.3 0.8  0.06 0.13 0.19   1:3.2                                 4.0    6.2    0.5 0.4  0.13 0.06 0.19 1.2:1                                   4.0    6.2    1.0 0.2  0.25 0.03 0.28 5:1                            test against E. coli in M9G medium                                            MBC2d   125.0   25.0   62.0                                                                              6.2  0.50 0.25 0.75 10:1                                   125.0   25.0   31.0                                                                              12.5 0.25 0.50 0.75 2.5:1                          test against a mixed culture in TSB medium                                    MIC     250.0   50.0  31.0 12.5 0.12 0.25 0.37 2.5:1                          MBC1d   250.0  200.0  62.0 25.0 0.25 0.13 0.37 2.5:1                          MBC2d   250.0  200.0  62.0 25.0 0.25 0.13 0.37 2.5:1                          MBC6d   250.0   50.0  31.0 12.5 0.12 0.25 0.37 2.5:1                          ______________________________________                                         The synergistic ratios of compound A:compound B range from 150:1 to 1:25.     The preferred ratios are 2.5:1 to 1:25.                                  

                  TABLE 10                                                        ______________________________________                                        Combination of Octhilinone and                                                3-Iodo-2-propynylbutylcarbamate                                               Compound A = Octhilinone                                                      Compound B = 3-Iodo-2-propynylbutylcarbamate                                  Method             calculations                                               of eval-                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                             uation QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                           ______________________________________                                        test against E. coli in TSB medium                                            MIC    250.0  200.0  125.0                                                                              100.0                                                                              0.50 0.50 1.00 1.2:1                           MBC2d  250.0  200.0  125.0                                                                              100.0                                                                              0.50 0.50 1.00 1.2:1                           MBC6d  250.0  200.0  125.0                                                                              100.0                                                                              0.50 0.50 1.00 1.2:1                           test against C. albicans in TSB medium                                        MIC     2.0    6.2    0.3  1.6 0.13 0.26 0.38   1:6.2                                 2.0    6.2    1.0  0.2 0.50 0.03 0.53 5:1                             MBC2d   2.0    6.2    0.5  1.6 0.25 0.26 0.51   1:3.1                                 2.0    6.2    1.0  0.2 0.50 0.03 0.53 5:1                             MBC6d   2.0    6.2    0.5  1.6 0.25 0.26 0.51   1:3.1                                 2.0    6.2    1.0  0.2 0.50 0.03 0.53 5:1                             test against E. coli in M9G medium                                            M9G     62.0   3.1    2.0  1.6 0.03 0.52 0.55 1.2:1                           MBC2d   62.0   50.0   31.0                                                                               3.1 0.50 0.06 0.56 10:1                                    62.0   50.0   2.0  25.0                                                                              0.03 0.50 0.53   1:12.5                        test against a mixed-culture in TSB medium                                    MIC    250.0  200.0   31.0                                                                              100.0                                                                              0.12 0.50 0.62   1:3.1                         MBC1d  250.0  400.0   31.0                                                                              100.0                                                                              0.12 0.25 0.37   1:3.1                         MBC2d  250.0  400.0   31.0                                                                              100.0                                                                              0.12 0.25 0.37   1:3.1                         MBC4d  250.0  200.0   31.0                                                                              100.0                                                                              0.12 0.50 0.62   1:3.1                         ______________________________________                                         The synergistic ratios of compound A:compound B range from 10:1 to 1:12.5     The preferred ratios are 5:1 to 1:3.1.                                   

                  TABLE 11                                                        ______________________________________                                        Combination of Octhilinone and 5-Hydroxypoly-                                 (methyleneoxy)-methyl-1-aza-3,7-dioxabicyclo(3,3,0)octane                     Compound A = Octhilinone                                                      Compound B = 5-Hydroxypoly(methyleneoxy)-                                     methyl-1-aza-3,7-dioxabicyclo(3,3,0)octane                                    Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in TSB medium                                            MIC    125.0   250.0  62.0 125.0                                                                              0.50 0.50 1.00 1:2                            MBC2d  125.0   500.0  31.0 250.0                                                                              0.25 0.50 0.75 1:8                                   125.0   500.0  62.0 125.0                                                                              0.50 0.25 0.75 1:2                            MBC6d  125.0   500.0   8.0 250.0                                                                              0.06 0.50 0.56  1:31                                 125.0   500.0  62.0 125.0                                                                              0.50 0.25 0.75 1:2                            test against C. albicans in TSB medium                                        MIC     2.0   1000.0   0.3  31.0                                                                              0.13 0.03 0.16  1:125                                 2.0   1000.0   1.0  0.5 0.50 0.00 0.50 2:1                            MBC2d   2.0   1000.0   0.3  31.0                                                                              0.13 0.03 0.16  1:125                                 2.0   1000.0   1.0  4.0 0.50 0.00 0.50 1:4                            MBC6d   2.0   1000.0   0.3  31.0                                                                              0.13 0.03 0.16  1:125                                 2.0   1000.0   1.0  4.0 0.50 0.00 0.50 1:4                            test against E. coli in M9G medium                                            MIC    125.0   62.0   31.0  31.0                                                                              0.25 0.50 0.75 1:1                            MBC1d  125.0   125.0  62.0  31.0                                                                              0.50 0.25 0.75 2:1                                   125.0   125.0  16.0  62.0                                                                              0.13 0.50 0.62 1:4                            test against a mixed-culture in TSB medium                                    MIC    250.0   500.0  31.0 125.0                                                                              0.12 0.25 0.37 1:4                            MBC1d  250.0  1000.0  31.0 125.0                                                                              0.12 0.13 0.25 1:4                            MBC2d  250.0   500.0  31.0 125.0                                                                              0.12 0.25 0.37 1:4                            MBC6d  250.0   500.0  31.0 125.0                                                                              0.12 0.25 0.37 1:4                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 2:1 to 1:125.      The preferred ratios are 1:4 to 1:31.                                    

                  TABLE 12                                                        ______________________________________                                        Combination of Octhilinone and Dipropylamine ether                            Compound A = Octhilinone                                                      Compound B = Dipropylamine ether                                              Method             calculations                                               of eval-                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                             uation QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                           ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0   31.0  2.0  16.0 0.02 0.52 0.53 1:8                                    125.0   31.0  8.0  8.0  0.06 0.26 0.32 1:1                                    125.0   31.0  62.0 2.0  0.50 0.06 0.56 31:1                            MBC1d  250.0   62.0  62.0 8.0  0.25 0.13 0.38 8:1                                    250.0   62.0  2.0  31.0 0.01 0.50 0.51  1:16                           MBC4d  125.0   31.0  16.0 16.0 0.13 0.52 0.64 1:1                                    125.0   31.0  62.0 2.0  0.50 0.06 0.56 31:1                            MBC7d  125.0   31.0  2.0  16.0 0.02 0.52 0.53 1:8                                    125.0   31.0  62.0 2.0  0.50 0.06 0.56 31:1                            test against C. albicans in TSB medium                                        MIC     1.3   125.0  0.6  16.0 0.50 0.13 0.62  1:25                           test against E. coli in TSB medium                                            MIC    125.0   50.0  31.0 6.2  0.25 0.12 0.37 5:1                                    125.0   50.0  8.0  12.5 0.06 0.25 0.31   1:1.6                         MBC1d  125.0   50.0  31.0 6.2  0.25 0.12 0.37 5:1                                    125.0   50.0  16.0 12.5 0.13 0.25 0.38 1.3:1                           MBC2d  125.0   50.0  31.0 6.2  0.25 0.12 0.37 5:1                                    125.0   50.0  16.0 12.5 0.13 0.25 0.38 1.3:1                           test against a mixed-culture in TSB medium                                    MIC    250.0  500.0  31.0 50.0 0.12 0.10 0.22   1:1.6                                250.0  500.0  62.0 25.0 0.25 0.05 0.30 2.5:1                           MBC6d  250.0  500.0  62.0 25.0 0.25 0.05 0.30 2.5:1                           ______________________________________                                         The synergistic ratios of compound A:compound B range from 8:1 to 1:25.       The preferred ratios are 2.5:1 to 1.6.                                   

                  TABLE 13                                                        ______________________________________                                        Combination of Octhilinone and Dodecylamine                                   Compound A = Octhilinone                                                      Compound B = Dodecylamine                                                     Method             calculations                                               of eval-                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                             uation QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                           ______________________________________                                        test against a mixed-culture in TSB medium                                    MIC    250.0  100.0  31.0 25.0 0.12 0.25 0.37 1.2:1                           MBC1d  250.0  200.0  31.0 25.0 0.12 0.13 0.25 1.2:1                           MBC2d  250.0  100.0  31.0 25.0 0.12 0.25 0.37 1.2:1                           MBC6d  250.0  100.0  31.0 25.0 0.12 0.25 0.37 1.2:1                           test against E. coli in M9G medium                                            MIC    125.0   25.0  62.0 6.2  0.50 0.25 0.75 10:1                                   125.0   25.0  31.0 12.5 0.25 0.50 0.75 2.5:1                           MBC1d  125.0   25.0  31.0 12.5 0.25 0.50 0.75 2.5:1                           MBC2d  125.0   25.0  31.0 12.5 0.25 0.50 0.75 2.5:1                                  125.0   25.0  62.0 6.2  0.50 0.25 0.75 10:1                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 10:1 to 1.2:1.     The preferred ratios are 2.5:1 to 1.2:1.                                 

                  TABLE 14                                                        ______________________________________                                        Combination of Octhilinone and N-(hydroxymethyl)-N'-                          (1,3-di(hydroxymethyl-2,5-dioxo-4-imidazolidinyl)-                            N'-(hydroxymethyl)urea                                                        Compound A = Octhilinone                                                      Compound B = N-(hydroxymethyl)-N'-(1,3-di(hydroxymethyl-                      2,5-dioxo-4-imidazolidinyl)-N'-(hydroxymethyl)urea                            Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against a mixed-culture in TSB medium                                    MIC    250.0   500.0  31.0 250.0                                                                              0.12 0.50 0.62 1:8                            MBC1d  250.0  1000.0  62.0 500.0                                                                              0.25 0.50 0.75 1:8                            MBC2d  250.0  1000.0  31.0 250.0                                                                              0.12 0.25 0.37 1:8                            MBC6d  250.0  1000.0  31.0 250.0                                                                              0.12 0.25 0.37 1:8                            test against E. coli in M9G medium                                            MIC    125.0   125.0  31.0  62.0                                                                              0.25 0.50 0.75 1:2                            MBC1d  250.0   500.0  16.0 125.0                                                                              0.06 0.25 0.31 1:8                                   250.0   500.0  31.0  62.0                                                                              0.12 0.12 0.25 1:2                                   250.0   500.0  62.0  31.0                                                                              0.25 0.06 0.31 2:1                            MBC4d  125.0   125.0  31.0  62.0                                                                              0.25 0.50 0.75 1:2                            MBC7d  125.0   125.0  31.0   62.0                                                                             0.25 0.50 0.75 1:2                            test against E. coli in TSB medium                                            MIC    125.0   500.0  62.0 250.0                                                                              0.50 0.50 1.00 1:4                            MBC2d  125.0  1000.0  31.0 500.0                                                                              0.25 0.50 0.75  1:16                                 125.0  1000.0  62.0 250.0                                                                              0.50 0.25 0.75 1:4                            MBC6d  125.0  1000.0   8.0 500.0                                                                              0.06 0.50 0.56  1:62                                 125.0  1000.0  62.0 250.0                                                                              0.50 0.25 0.75 1:4                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 2:1 to 1:62.       The preferred ratios are 1:2 to 1:8.                                     

                  TABLE 15                                                        ______________________________________                                        Combination of Octhilinone and 1-(3-Chloroallyl)-3,5,7-                       triaza-1-azoniaadamantane chloride                                            Compound A = Octhilinone                                                      Compound B = 1-(3-Chloroallyl)-3,5,7-triaza-1-                                azoniaadamantane chloride                                                     Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0   125.0  16.0  62.0                                                                              0.13 0.50 0.62 1:4                                   125.0   125.0  62.0  31.0                                                                              0.50 0.25 0.74 2:1                            MBC1d  250.0  1000.0  62.0 125.0                                                                              0.25 0.13 0.37 1:2                                   250.0  1000.0  31.0 250.0                                                                              0.12 0.25 0.37 1:8                                   250.0  1000.0  8.0  500.0                                                                              0.03 0.50 0.53 1:62.5                         MBC4d  125.0   125.0  16.0  62.0                                                                              0.13 0.50 0.62 1:4                                   125.0   125.0  62.0  31.0                                                                              0.50 0.25 0.74 2:1                            MBC7d  125.0   125.0  16.0  62.0                                                                              013  0.50 0.62 1:4                                   125.0   125.0  62.0  31.0                                                                              0.50 0.25 0.74 2:1                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 2:1 to 1:62.5.     The preferred ratios are 2:1 to 1:4.                                     

                  TABLE 16                                                        ______________________________________                                        Combination of Octhilinone and                                                1,2-Dibromo-2,4-dicyanobutane                                                 Compound A = Octhilinone                                                      Compound B = 1,2-Dibromo-2,4-dicyanobutane                                    Method             calculations                                               of eval-                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                             uation QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                           ______________________________________                                        test against E. coli in TSB medium                                            MIC    125.0  250.0  31.0 50.0 0.25 0.20 0.45   1:1.6                         MBC2d  125.0  250.0  62.0 50.0 0.50 0.20 0.70 1.2:1                           MBC6d  125.0  250.0  62.0 50.0 0.50 0.20 0.70 1.2:1                           test against C. albicans in TSB medium                                        MIC     2.5    62.0  1.3  4.0  0.50 0.06 0.56   1:3.2                                 2.5    62.0  0.6  16.0 0.25 0.26 0.51  1:25                           test against E. coli in M9G medium                                            MIC     62.0   25.0  31.0 3.1  0.50 0.12 0.62 10:1                                    62.0   25.0  8.0  6.2  0.13 0.25 0.38 1.2:1                                   62.0   25.0  4.0  12.5 0.06 0.50 0.56   1:3.2                         MBC1d   62.0  100.0  31.0 3.1  0.50 0.03 0.53   1:1.6                                 62.0  100.0  8.0  12.5 0.13 0.13 0.25   1:1.6                                 62.0  100.0  4.0  50.0 0.06 0.50 0.56   1:12.5                        test against a mixed-culture in TSB medium                                    MIC    250.0   50.0  16.0 25.0 0.06 0.50 0.56   1:1.6                         MBC1d  250.0  400.0  62.0 50.0 0.25 0.13 0.37 1.2:1                           MBC2d  250.0  200.0  31.0 50.0 0.12 0.25 0.37   1:1.6                         MBC6d  250.0  200.0  16.0 25.0 0.06 0.13 0.19   1:1.6                         ______________________________________                                         The synergistic ratios of compound A:compound B range from 10:1 to 1:25.      The preferred ratios are 1.2:1 to 1:3.2.                                 

                  TABLE 17                                                        ______________________________________                                        Combination of Octhilinone and N,N-dimethyl-N'-phenyl-N'-                     (fluorodichloromethylthio)sulfamide                                           Compound A = Octhilinone                                                      Compound B = N,N-dimethyl-N'-phenyl-N'-                                                    (fluorodichloromethylthio)sulfamide                                                calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evalutaion                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC     125.0  500.0  62.0  62.0                                                                              0.50 0.12 0.62 1:1                                    125.0  500.0  31.0 125.0                                                                              0.25 0.25 0.50 1:4                            MBC1d   125.0  500.0  62.0  62.0                                                                              0.50 0.12 0.62 1:1                            test against C. albicans in TSB medium                                        MIC      2.5   500.0   1.3 125.0                                                                              0.50 0.25 0.75  1:100                         ______________________________________                                         The synergistic ratios of compound A:compound B range from 1:1 to 1:100.      The preferred ratios are 1:1 to 1:4.                                     

                  TABLE 18                                                        ______________________________________                                        Combination of Octhilinone and N,N'-dihydroxymethyl-5,5'-                     dimethylhydantoin                                                             Compound A =   Octhilinone                                                    Compound B =   N,N'-dihydroxymethyl-5,5'-                                                    dimethylhydantoin                                              Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0   250.0   8.0 125.0                                                                              0.06 0.50 0.56  1:15                          MBC1d  125.0   250.0   8.0 125.0                                                                              0.06 0.50 0.56  1:15                          test against mixed culture in TSB medium                                      MIC    250.0  2000.0  62.0 500.0                                                                              0.25 0.25 0.50 1:8                            MBC1d  250.0  2000.0  62.0 500.0                                                                              0.25 0.25 0.50 1:8                            MBC2d  250.0  2000.0  62.0 500.0                                                                              0.25 0.25 0.50 1:8                            MBC6d  250.0  2000.0  62.0 500.0                                                                              0.25 0.25 0.50 1:8                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 1:8 to 1:15.       The preferred ratios are 1:8 to 1:15.                                    

                  TABLE 19                                                        ______________________________________                                        Combination of Octhilinone and 2-Bromo-2-nitropropanediol                     Compound A =   Octhilinone                                                    Compound B =   2-Bromo-2-nitropropanediol                                                       calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evalutaion                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MBC1d   125.0   8.0   16.0 4.0  0.13 0.50 0.63 4:1                            test against C. albicans in TSB medium                                        MIC      2.5   62.0   0.1  31.0 0.03 0.50 0.53  1:400                                  2.5   62.0   0.6  16.0 0.25 0.26 0.51  1:25                                   2.5   62.0   1.3  5.0  0.50 0.08 0.58 1:4                            test against a mixed-culture in TSB medium                                    MIC     250.0   4.0   4.0  2.0  0.02 0.50 0.52 2:1                            MBC1d   250.0  32.0   16.0 8.0  0.06 0.25 0.31 2:1                            MBC2d   250.0  16.0   8.0  4.0  0.03 0.25 0.28 2:1                            MBC6d   250.0   8.0   4.0  2.0  0.02 0.25 0.27 2:1                            ______________________________________                                         The synergistic ratios of compound A:compound B range from 4:1 to 1:400.      The preferred ratios are 4:1 to 1:4.                                     

                  TABLE 20                                                        ______________________________________                                        Combination of Octhilinone and Methylene-bis-thiocyanate                      Compound A =   Octhilinone                                                    Compound B =   Methylene-bis-thiocyanate                                      Method              calculations                                              of eval-                                                                             end-point activity in ppm                                                                      Qa/    Qb/                                            uation QA     QB      Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC    125.0  4.0      16.0                                                                              2.0  0.13 0.50 0.63  8:1                                  125.0  4.0      62.0                                                                              1.0  0.50 0.25 0.75 62:1                           MBC1d  250.0  31.0     62.0                                                                              16.0 0.25 0.52 0.77  4:1                                  250.0  31.0    125.0                                                                              4.0  0.50 0.13 0.63 31:1                           MBC4d  125.0  4.0      31.0                                                                              2.0  0.25 0.50 0.75 16:1                           MBC7d  125.0  4.0      31.0                                                                              2.0  0.25 0.50 0.75 16:1                                  125.0  4.0      62.0                                                                              1.0  0.50 0.25 0.75 62:1                           test against C. albicans in TSB medium                                        MIC     2.5   6.2      0.2 3.1  0.06 0.50 0.56  1:20                                  2.5   6.2      0.6 1.6  0.25 0.26 0.51   1:2.5                                2.5   6.2      1.3 0.8  0.50 0.13 0.63 1.6:1                          test against a mixed-culture in TSB medium                                    MBC1d  250.0  100.0    25.0                                                                              50.0 0.10 0.50 0.60  1:2                           MBC2d  250.0  100.0    25.0                                                                              50.0 0.10 0.50 0.60  1:2                           MBC6d  250.0  12.5     3.1 6.2  0.01 0.50 0.51  1:2                           ______________________________________                                         The synergistic ratios of compound A:compound B range from 62:1 to 1:20.      The preferred ratios are 16:1 to 1:2.                                    

                  TABLE 21                                                        ______________________________________                                        Combination of Octhilinone and 2,4-Dichlorobenzyl alcohol                     Compound A =   Octhilinone                                                    Compound B =   2,4-dichlorobenzyl alcohol                                                       calculations                                                Method of                                                                             end-point activity in ppm                                                                     Qa/    Qb/                                            evalutaion                                                                            QA     QB     Qa   Qb   QA   QB   SI   Qa:Qb                          ______________________________________                                        test against E. coli in M9G medium                                            MIC     125.0   62.0  62.0 16.0 0.50 0.26 0.75 4:1                            MBC1d   250.0  125.0  31.0 62.0 0.12 0.50 0.62 1:2                                    250.0  125.0  62.0 31.0 0.25 0.25 0.50 2:1                            MBC4d   125.0  125.0  31.0 62.0 0.25 0.50 0.75 1:2                                    125.0  125.0  62.0 31.0 0.50 0.25 0.75 2:1                            MBC7d   125.0  125.0  31.0 62.0 0.25 0.50 0.75 1:2                                    125.0  125.0  62.0 16.0 0.50 0.13 0.62 4:1                            test against C. albicans in TSB medium                                        MIC      2.5   125.0   1.3  8.0 0.50 0.06 0.56   1:6.2                        ______________________________________                                         The synergistic ratios of compound A:compound B range from 4:1 to 1:6.2.      The preferred ratios are 4:1 to 1:2.                                     

                  TABLE 22                                                        ______________________________________                                        combination of Octhilinone and Sodium dichlorophene                           Compound A =    Octhilinone                                                   Compound B =    Sodium dichlorophene                                          Method of                                                                             end-point activity in ppm                                                                       calculations                                        evaluation                                                                            QA      QB     Qa   Qb    Qa/QA Qb/QB SI                              ______________________________________                                        test against E. coli in M9G medium                                            MIC     125.0   16.0   125.0                                                                              16.0  NA    NA    NA                              MBC1d   250.0   16.0   250.0                                                                              16.0  NA    NA    NA                              MBC4d   125.0   16.0   125.0                                                                              16.0  NA    NA    NA                              MBC7d   125.0   16.0   125.0                                                                              16.0  NA    NA    NA                              test against E. coli in TSB medium                                            MIC     125.0   62.0   125.0                                                                              62.0  NA    NA    NA                              MBC1d   125.0   62.0   125.0                                                                              62.0  NA    NA    NA                              test against C. albicans in TSB medium                                        MIC      2.5    50.0    1.3 25.0  0.50  0.50  1.00                            ______________________________________                                         NA = not applicable because it is not endpoint of activity.              

As can be seen by review of Table 1-21, the compositions demonstratesynergistic antimicrobial activities as measured by minimum inhibitoryconcentrations (MIC) and synergistic biocidal activity as measured byminimum biocidal concentrations (MBC), and show surprisingly greateractivity than the algebraic sum of the individual ingredients which makeup the respective composition.

In contrast, an example of non-synergistic combination of octhilinoneand sodium dichlorophene is in Table 22. In this example ofnon-synergism, the antibacterial activities of either octhilinone orsodium dichlorophene as measured by the activities against E. coli arenot affected by the presence or the absence of the other component inthe combination. It is also not antagonistic because no loss of activityof either component in the combination was detected. The antifungalactivity, as measured by activity against C. albicans, indeed increasedas a result of the combination. The increased activity, however, ismerely additive because the synergy index is 1.

The synergistic activities in most cases are applicable to bacterial,fungi, and a mixture of bacteria and fungi. Thus, the combinations notonly lower the use-level of biocide but also broaden the spectrum ofactivity. This is especially useful in situations where either componentalone does not achieve the best results due to weak activity againstcertain organisms. For octhilinone combinations, the synergisticactivity against Gram-negative bacteria is most significant insituations where both bacteria and fungi are present in the system.

Another example is provided below to demonstrate the advantage of usingocthilinone-containing compositions. In this example, a combination ofocthilinone and5-hydroxypoly(methyleneoxy)-methyl-1-aza-3,7-dioxabicyclo(3,3,0)octane(DBO) was evaluated for the control of fouling bacterial and fungi in ametalworking fluid. The test was a 4-week multiple challenge efficacytest. Octhilinone, DBO, and the combination of octhilinone and DBO wereadded to specified concentrations into 50 ml use dilution of themetalworking fluid in 4 oz. jars. Each jar was then inoculated weeklywith a mixed culture of bacteria and fungi isolated from naturallycontaminated metalworking fluid to make final concentration of about2×10⁶ fungi and 2×10⁷ bacterial per ml of fluid. The viable counts weredetermined 7 days after each inoculation by 10-fold serial dilutions andplatings on Trypicase Soy Agar (Difco) for bacterial and on Rose BengalAgar with 100 ppm chloramphenicol (Oxoid) for fungi. Results of suchtests are shown in Table 23. Rating of efficacy is based on generallyaccepted criteria in the metalworking fluid industry that >10⁵ bacteriaor 10³ fungi per ml failed the efficacy test, and less than 10⁵bacterial and 10³ fungi passed the test. When a biocide passes all 4weekly challenge tests, it will effectively preserve the metalworkingfluid. It is evident after examining Table 24 that a mixture ofocthilinone and DBO preferably at ratios from 1:4 to 1:31, provides astrong synergism and effective control of bacteria, fungi, and the mixedculture of bacteria and fungi. In fact, either octhilinone or DBO is notused as a general biocide in preserving metalworking fluid due to highdosage requirement and thereby cost disadvantage. Now, with thesynergistic combination of octhilinone and DBO they can be usedeffectively as a general biocide for preserving metalworking fluids.

                  TABLE 23                                                        ______________________________________                                        Efficacy Test on Combinations of Octhilinone and DBO                          in a Metalworking Fluid                                                       Treatment                                                                     Sample                                                                              Octhilinone                                                                             DBO      Efficacy*                                            Nos.  ppm a.i.  ppm a.i. 1 Wk. 2 Wks.                                                                              3 Wks.                                                                              4 Wks.                             ______________________________________                                         1    0          0       4     4     4     4                                   2    0         125      2     2     4     4                                   3    0         250      2     2     4     4                                   4    0         500      2     2     2     4                                   5    0         750      0     2     2     4                                   6    0         1000     0     0     0     2                                   7    0         1250     0     0     0     0                                   8    4          0       3     4     4     4                                   9    8          0       3     3     3     4                                  10    16         0       3     3     3     4                                  11    32         0       3     3     3     3                                  12    64         0       3     3     3     3                                  13    4         250      0     0     2     4                                  14    8         250      0     0     0     0                                  15    16        250      0     0     0     0                                  16    32        250      0     0     0     0                                  17    64        250      0     0     0     0                                  18    4         500      0     0     2     2                                  19    8         500      0     0     0     0                                  20    16        500      0     0     0     0                                  21    32        500      0     0     0     0                                  22    64        500      0     0     0     0                                  23    4         750      0     0     0     0                                  24    8         750      0     0     0     0                                  25    16        750      0     0     0     0                                  26    32        750      0     0     0     0                                  27    64        750      0     0     0     0                                  ______________________________________                                         4 = failed both bacteria (>10.sup.5 cfu/ml) and fungi (>10.sup.3 cfu/ml)      3 = failed bacteria only                                                      2 = failed fungi only                                                         0 = passed both bacteria (<10.sup.5 cfu/ml) and fungi (<10.sup.3 cfu/ml) 

                                      TABLE 24                                    __________________________________________________________________________    Calculations for Synergy Index (SI) of Octhilinone (A) and DBO (B)            Combinations                                                                         Ratio                                                                  Sample Nos.                                                                          (a):(b)                                                                           SI for Bacteria*                                                                           SI for Fungi SI for Mixed Culture*                    __________________________________________________________________________    14     1:31                                                                              250/1000 + 8/500  = 0.26                                                                   250/1250 + 8/32  = 0.45                                                                    250/1250 + 8/500  = 0.21                 15     1:15                                                                              250/1000 + 16/500 = 0.28                                                                   250/1250 + 16/32 = 0.75                                                                    250/1250 + 16/500 = 0.23                 16     1:8 250/1000 + 32/500 = 0.31                                                                    NA**        250/2250 + 32/500 = 0.26                 17     1:4 250/1000 + 64/500 = 0.37                                                                   NA           250/1250 + 64/500 = 0.32                 18      1:125                                                                            500/1000 + 4/500  = 0.50                                                                   NA           NA                                       19     1:62                                                                              500/1000 + 8/500  = 0.51                                                                   500/1250 + 8/500 = 0.65                                                                    500/1250 + 8/500  = 0.41                 20     1:31                                                                              500/1000 + 16/500 = 0.53                                                                   500/1250 + 16/32 = 0.90                                                                    500/1250 + 16/500 = 0.43                 21     1:16                                                                              500/1000 + 32/500 =  0.56                                                                  NA           500/1250 + 32/500 = 0.46                 22     1:8 500/1000 + 64/500 = 0.62                                                                   NA           500/1250 + 64/500 = 0.52                 23      1:187                                                                            750/1000 + 4/500  = 0.75                                                                   750/1250 + 4/32  = 0.88                                                                    750/1250 + 4/500  = 0.60                 24     1:94                                                                              750/1000 + 8/500  = 0.76                                                                   NA           750/1250 + 8/500  = 0.61                 25     1:47                                                                              750/1000 + 16/500 = 0.78                                                                   NA           750/1250 + 16/500 = 0.63                 26     1:23                                                                              750/1000 + 32/500 = 0.81                                                                   NA           750/1250 + 32/500 = 0.66                 27     1:12                                                                              750/1000 + 64/500 = 0.87                                                                   NA           750/1250 + 64/500 = 0.72                 __________________________________________________________________________     The endpoint activity of Octhilinone against bacteria and the mixed           culture was independently determined to be 500 ppm.                           **NA = Not applicable because they are not end points                    

What is claimed:
 1. A microbicidal composition comprising a synergisticmixture the first component of which is 2-n-octyl-4-isothiazolin-3-oneand the second component of which is α-benzoyl-α-chloroformaldoximewherein the ratio of first component to second component is in the rangeof from about 62:1 to about 1:100.
 2. A method for inhibiting the growthof a member selected from the group consisting of bacteria, fungi, algaeand mixtures thereof in a locus subject to contamination by said member,which comprises incorporating onto or into the locus, in an amount whichis effective to adversely affect the growth of said member, thecomposition of claim
 1. 3. The method of claim 2 wherein the locus is anaqueous medium.
 4. The method of claim 3 wherein the composition isbetween from about 20 to about 400 ppm.
 5. The method of claim 3 whereinthe composition is between from about 25 to about 200 ppm.
 6. A productcontaining from about 20 to 400 ppm of the composition of claim 1.